Technology and industry has relied substantially on the use, by-products and energy, of oil and oil-based products. In fact, this reliance continues to grow, with the result that accidents with oil based products will occur with greater frequency causing oil pollution, sometimes of a serious nature.
Various approaches have been used in combating or remediating oil related pollution. In this regard, the remediation industry has relied primarily on mechanical devices and methods to remove contamination from the affected area. Unfortunately, these methods are not always satisfactory. In certain instances, the mechanical solution results in the pollutant merely being moved off site. In an even worse situation, the pollutant is transferred to another medium, such as the air, through burning. The process by which these mechanical devices “remove” the contaminant can often be as destructive to the environment as the original pollution itself.
Another approach to pollution cleanup has been through the use of microorganisms. It is known that there exists a well established, highly diverse population of microorganisms that degrade petroleum hydrocarbons. The application or utilization of petroleum degrading microorganisms in spilled oil situations is known generally as the process or method of bioremediation. Bioremediation has been successfully used to treat contaminated soil in above-ground treatment systems, above-ground slurry bioreactors, slurry pits, above-ground soil heaps, composting material, and in situ. A good example showing the use of in situ soil treatment by microorganisms followed the Exxon Valdez oil spill in Prince William Sound, Ak. in 1989. This spilled oil contaminated miles of Alaskan shoreline. An approximately 70 mile section of shoreline was treated using bioremediation techniques. One aspect of the remediation process employed in Prince William Sound focused on enhancing the indigenous microorganisms' growth and oil degrading activities through the application of nutrients (see Roger Prince, et al. 1993 “Bioremediation of the Exxon Valdez Oil Spill: Monitoring Safety and Efficacy,” Lewis Publishers; 107-124; 1994).
Unfortunately, there are a number of shortcomings in existing bioremediation technologies. For example, the Inipol technology advanced by the French contains a stabilizer in amounts that exceed OSHA exposure limits. This apparently has led to several reported health claims to the Alaska Worker's Compensation Board (see, for example, Roberts vs Veco, 1996 Alaska Worker's Compensation Board, AWCB Case #9034054, AWCB Decision #96-0029), and severely restricted the product's use.
The exposure limits established by OSHA often in fact prevent the use of many bioremediation products in enclosed environments, such as within a plant structure. It is recognized that worker exposure to bioremediation products may be a far greater health risk than the hydrocarbon contamination itself. Therefore, within these areas, standard degreasers substitute as clean up techniques for the more effective and environmentally sound use of bioremediation.
Another limitation preventing the widespread use of bioremediation in active work sites is the flammability issue. Refineries and terminals, which are key handlers of oil and thus key sites of hydrocarbon contamination, have strict safety procedures regulating the use and transportation of flammable material within active facilities. These regulations are also followed by DOT, OSHA and other agencies supervising the use of flammable and combustible products.
The Exxon Valdez oil spill identified the enhanced effectiveness of hydrophobic microemulsions over traditional hydrophilic nutrients (see Roger C. Prince, et al. 1993 “Laboratory Studies of Oil Spill Bioremediation; Towards understanding field behavior,” Exxon Research and Engineering.). However, traditional ingredients chosen for the microemulsion to advance “environmentally sound” technology were not environmentally sound themselves. This gap between appropriate available technology and the market need has prevented the widespread use of bioremediation. The solution to bridging this gap began with understanding the advantages and shortcomings of existing technology and applying “environmental” criteria to advance the performance of bioremediation methods.
A number of factors determine the effectiveness of the bioremediation process. First, there must be hydrocarbon degrading microorganisms present, either indigenous or through addition. Second, there must be oxygen and water available to permit the microorganisms to be metabolically active. Third, there must also be available sufficient quantities of biologically utilizable nitrogen and phosphorous to enable the microbial population to rapidly metabolize the available petroleum hydrocarbons. As significant quantities of petroleum pollute a medium (water, shoreline, or soil), essential nutrients must be applied to the petroleum to sustain microbial growth.
U.S. Pat. No. 4,460,692 (Tellier) discloses a microemulsion made of a nutrient formulation comprising a hydrophobic external phase and an internal water-soluble internal core. The stabilizer package is chosen for its volatility and is listed as butyl ether of ethylene glycol, an undesirable product on the OSHA exposure list.
U.S. Pat. No. 3,883,397 (Townsky) discloses a particulate material made of a nutrient formulation coated with a lipophilic material that suspends the material in the oil or near the oil-water interface. This coating is composed of magnesium, aluminum and calcium salts of lipophilic fatty acids, specifically magnesium stearate.
U.S. Pat. No. 5,725,885 (Felix) discloses a composition that is broader than either listed in the above patents. The use of oxygen generating materials clearly advances the rate of bioremediation, but compromises the very issues holding the market back from utilizing the process. The toxicity and flammability of peroxide containing compounds is an industrial concern.
U.S. Pat. No. 5,384,048 (Hazen) describes an apparatus and a nutrient fluid to stimulate the natural degradation of chlorinated hydrocarbons. Unfortunately, the carbon source, methane, is highly combustible, limiting the commercial use of Hazen in bioremediation contexts.